TP53 and retinoblastoma: A survey of five proteins targeted by various Cullin complexes (p53, p21, p27, p130, and CTD1) suggested that MLN4924 has distinct molecular effects in different RB tumors; for example, p27 was more potently induced in RB3823 MYCNamp cells versus RB1null cells, but p21 showed the opposite behavior; p130 was only induced (albeit modestly) in the hypersensitive lines RB1021 and RB3823; and while p53 and CDT1 were induced ubiquitously, the response was earlier in these hypersensitive cells (Supplementary Fig. 3).